1. Field of the Invention
This invention relates to providing hot water to the end user, in particular, for providing hot water substantially instantaneously to the user upon activation of the faucet.
2. Background of the Invention
In a typical household or apartment setting, obtaining hot water from a faucet requires the user to wait for a period of time, sometimes as long as several minutes, after turning on the faucet. This delay is primarily because the heating tank is usually located in the basement of the building or somewhere far from the faucet being used. Remote placement of the heating tank is common in North America and other regions where the space near the faucet, such as in kitchens and bathrooms, is limited. When the faucet is not turned on, the water in the piping between the hot water source and faucet loses its heat to the surroundings. Due to the substantial amount of piping in some homes and the corresponding exposed surface area of the water contained therein, after a minimal amount of time, the water drops to room temperature. As a result, all of this standing water must be flushed out before hot water from the water heater reaches the faucet. In addition, while waiting for the standing water in the pipes to exit the faucet, users generally continue to adjust the hot and cold dials, often overcompensating the percentage of hot or cold water, until the desired temperature is reached. The desired temperature, however, is only consistently maintained after all the standing water in the hot water pipes has been flushed out.
One of the simplest and cheapest solutions to mitigate this problem is to place the water heater closer to the faucet. An obvious drawback is that the limited space in bathrooms and kitchens cannot comfortably or aesthetically accommodate a 30 or 40 gallon water heater. In addition, multiple tanks throughout the house is not energy efficient.
Point-of-use heaters, which are currently available, heat water only as needed. They are generally smaller than conventional water tanks so they can be located in the same room as the faucet, although they cannot be readily concealed behind a wall. Moreover, point-of-use gas heaters require additional lines for the gas, a ventilation system for air intake, and an exhaust for combustion. Industrial point-of-use heaters, on the other hand, require substantial electrical power which is typically too much for the home. Electrically powered point-of-use heaters designed for residential use only raise the water temperature to take the "chill out." They are more common in warmer climates where the heating requirements are less.
Finally, hot water can be recirculated to keep the water in the hot water pipes hot. This type of system is mostly used for hotels and large buildings, and the cost of implementing such a system for a residential home is prohibitively expensive.
One company, In-Sink-Erator.TM., sells a system for providing water at 190.degree. F. instantly for making hot drinks. The system essentially comprises a separate faucet attached to a small heated reservoir under the sink. This device, called Steamin' Hot.TM., provides water at a temperature normally not obtainable through conventional water heaters because many states regulate the maximum water heater temperature setting to prevent scalding. This product, however, does not address the present problem of the time delay and temperature fluctuation associated with faucets and showers.
Merloni Termo Sanitari Company manufactures a product called Ariston.TM. which is a small water heater with a 2.4 or 4 gallon capacity. Although much smaller than a conventional water heater, it requires bulky insulation and is not designed to fit inside the walls of a house. More importantly, it does not keep the hot water inside the tank separate from the incoming cool water. This is essential for smaller tanks to provide uninterrupted hot water until the hot water from the hot water pipe arrives.
Currently, there are patents and devices on the market regulating water temperature through the use of servo controlled valves. Home use applications, however, have been limited primarily because of the high cost of the devices. Recently, Hass Mfg..TM. and American Standard.TM. have offered temperature regulating control systems called Intelli Faucet.TM. and Ultra Valve.TM., respectively. All of these temperature regulation means require a hot and a cold water supply source. Because these devices do not heat the water, they cannot provide the desired water temperature if the water in the hot water pipe is cooler than the desired water temperature. Thus, these temperature controllers cannot avoid the delay caused while flushing standing water from the hot water pipes.
Sprague, U.S. Pat. No. 4,551,612, describes a water heating tank that can be installed inside a wall as a replacement for conventional water heating tanks. The patent describes a method for conserving space required by conventional water heaters. However, the Sprague water heater, having a thin profile, becomes larger and the surface area to volume ratio increases resulting in extraneous energy waste. In addition, the structural strength of the water tank must be made stronger to support the water if one were to use the Sprague device to replace a conventional tank.